2.0 Analysis 2.1 General The lack of an automated ground-based conflict detection and alerting system and the lack of regulations requiring transport aircraft to be equipped with TCAS continues to put air travellers at risk. Although Nav Canada has been working on the development and deployment of a radar-based automated conflict detection and alerting system, the company has been unsuccessful to date. Transport Canada intends to amend the Canadian Aviation Regulations to require passenger-carrying transport aircraft to be equipped with TCAS within the next few years. These issues will not be further analyzed in this report. The remainder of the analysis will deal with the issues of controller situational awareness, controller work practices, and management practices. 2.2 Situational Awareness From the time the second controller took over responsibility for the west sector position at approximately 1845, he did not have all the information necessary to ensure that his mental model of the traffic situation__his situational awareness__was correct. Looking at the RSiT, he concluded, based on previous experience of seeing up to four aircraft from this airline flying eastbound at this time of day, that both Lufthansa flights must be eastbound. Two additional factors reinforced his mental model. First, it was not his practice to use a normally eastbound altitude (FL370) for westbound aircraft close to the cut-off time of 1900. In fact, among the controllers there were differences in work practices related to the use of the structured altitude procedures within Gander ACC domestic airspace. Second, due to the long range displayed on the RSiT, the trail dots shown behind each radar target were smaller and harder to see. There is no standardized method for indicating direction of flight on the radar IMs. The second controller did not, therefore, detect that DLH420 was flying westbound. Since information concerning a potential conflict was not passed between the two controllers at the handover briefing, the second controller did not see any requirement to immediately complete a detailed check of the flight progress strips. This resulted in the second controller having reduced situational awareness and not detecting that the two aircraft were on converging courses. Procedural defences were in place to help the controllers gather correct and current information and so develop accurate mental models of the air traffic situation. However, neither controller used the defences consistently in this occurrence. The first controller did not highlight strips for the two aircraft to indicate a potential conflict, the strip for DLH411 was not cocked to indicate an uncompleted action, nor was the altitude marked to indicate that DLH411 was flying at an altitude not in accordance with the current structure for the airspace. 2.3 Controller Work Practice Defences The defences provided by following published strip-marking procedures__such as indicating the potential conflict on each strip, marking altitudes not appropriate for direction of flight, and cocking strips__were not used and, therefore, were ineffective in preventing this occurrence. The first controller had not expected to leave his operating position so quickly and before solving the conflict between the two aircraft. A clue to the direction of flight, the differently coloured printing on the strips, was not effective as a defence because the controller had not yet progressed, in his board check, to a review of the strips for the two Lufthansa aircraft. The controller did not provide traffic information or use established safety-alerting phraseology. Consequently, the pilot of DLH420 initially selected a normal rate of descent, rather than one reflecting the urgency of the situation. This increased the time needed to achieve the required 1000-foot vertical spacing between the two aircraft and thereby lengthened the time the two aircraft were at risk. 2.4 Management Practices Although handover checklists were available in Gander ACC, there is no stated requirement directing controllers to use the checklist during transfer of position responsibility briefings. Had the two controllers been required to refer to the checklist, critical information concerning the two aircraft flying toward each other at the same altitude would likely have come to light. Since controllers are not required to use handover checklists during handover briefings, there is a continued risk that critical information could be overlooked, thereby leading to losses of separation or midair collisions. ATC units have standardized methods to indicate direction of flight on flight progress strips, but not to show direction of flight on the IM. The direction of flight can be shown by colour-coded printing on the flight progress strip or by printing the aircraft identification at the appropriate end of the strip. Controllers have a number of techniques and tools on the IM, but the choice of which to use (or not to use) is left to each controller. This is not consistent with the principle established for standardized coding of strips for direction of flight. In this occurrence, had a standard method for depiction of flight on the IM been established and used by all controllers, the second controller might have been alerted to the two Lufthansa aircraft flying toward each other. 3.0 Conclusions 3.1 Findings as to Causes and Contributing Factors The handover briefing between the two controllers was incomplete, and the available position handover checklist was not used. These actions deprived the second controller of critical information about the conflict between the two aircraft. The first controller did not use standard work practices, as required by published procedures. As a result, the second controller did not detect critical information pertaining to the two aircraft. The second controller misinterpreted the direction of flight of DLH420. Consequently, he was not aware that this aircraft was in conflict with DLH411. The second controller did not complete a flight progress board check in the few minutes between assuming control of the position and the time of the occurrence. This eliminated the defence provided by the colour-coded printing on the strips. 3.2 Findings as to Risk There are no written requirements mandating controllers to use the available handover checklist during transfer of position briefings. As a result, the checklists are used only sporadically, which can lead to information being missed during the many times that handovers take place in the course of a day. There is no standard method by which controllers depict direction of flight on the radar indicator module; this can lead to information being overlooked or misinterpreted. Although required by published air traffic control procedures, the altitude on the strip for DLH411 was not marked as wrong way. This omission may have reduced the likelihood of the oncoming controller detecting the conflict. An automated conflict-alerting system is not yet available to alert Canadian controllers of impending air traffic conflicts; however, a system is being developed. The second controller did not use the approved safety-alerting phraseology to instruct the pilot of DLH420 to descend to flight level 360. As a result, the two aircraft were exposed to a risk of collision for longer than necessary, and there was a delay in achieving the required minimum 1000-foot vertical spacing. As a result of this occurrence, Gander Area Control Centre (ACC) has included a mandatory requirement for controllers to complete the briefing checklist when assuming responsibility for a sector. This action was initiated on 15 August 2000, and the Gander Unit Operations Manual was updated on 22 March 2001. On 18 April 2001, the TSB forwarded Aviation Safety Information Letter A000043-1 to Nav Canada to encourage consideration of a method, applicable to all Air Traffic Services units across the country, to reduce the risks associated with memory-dependent transfer of position responsibility briefings and to ensure that critical information will not be forgotten.4.0 Safety Action Taken As a result of this occurrence, Gander Area Control Centre (ACC) has included a mandatory requirement for controllers to complete the briefing checklist when assuming responsibility for a sector. This action was initiated on 15 August 2000, and the Gander Unit Operations Manual was updated on 22 March 2001. On 18 April 2001, the TSB forwarded Aviation Safety Information Letter A000043-1 to Nav Canada to encourage consideration of a method, applicable to all Air Traffic Services units across the country, to reduce the risks associated with memory-dependent transfer of position responsibility briefings and to ensure that critical information will not be forgotten.